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[NET]: Added GSO header verification
[net-next-2.6.git] / include / net / tcp.h
CommitLineData
1da177e4
LT		 1/*
2 * INET An implementation of the TCP/IP protocol suite for the LINUX
3 * operating system. INET is implemented using the BSD Socket
4 * interface as the means of communication with the user level.
5 *
6 * Definitions for the TCP module.
7 *
8 * Version: @(#)tcp.h 1.0.5 05/23/93
9 *
02c30a84 10 * Authors: Ross Biro
1da177e4
LT		 11 * Fred N. van Kempen, <waltje@uWalt.NL.Mugnet.ORG>
12 *
13 * This program is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU General Public License
15 * as published by the Free Software Foundation; either version
16 * 2 of the License, or (at your option) any later version.
17 */
18#ifndef _TCP_H
19#define _TCP_H
20
21#define TCP_DEBUG 1
22#define FASTRETRANS_DEBUG 1
23
1da177e4
LT		 24#include <linux/list.h>
25#include <linux/tcp.h>
26#include <linux/slab.h>
27#include <linux/cache.h>
28#include <linux/percpu.h>
fb286bb2 29#include <linux/skbuff.h>
97fc2f08 30#include <linux/dmaengine.h>
3f421baa
ACM		 31
32#include <net/inet_connection_sock.h>
295ff7ed 33#include <net/inet_timewait_sock.h>
77d8bf9c 34#include <net/inet_hashtables.h>
1da177e4 35#include <net/checksum.h>
2e6599cb 36#include <net/request_sock.h>
1da177e4
LT		 37#include <net/sock.h>
38#include <net/snmp.h>
39#include <net/ip.h>
c752f073
ACM		 40#include <net/tcp_states.h>
41
1da177e4
LT		 42#include <linux/seq_file.h>
43
6e04e021 44extern struct inet_hashinfo tcp_hashinfo;
1da177e4 45
1da177e4 46extern atomic_t tcp_orphan_count;
1da177e4 47extern void tcp_time_wait(struct sock *sk, int state, int timeo);
1da177e4 48
1da177e4
LT		 49#define MAX_TCP_HEADER (128 + MAX_HEADER)
50
51/*
52 * Never offer a window over 32767 without using window scaling. Some
53 * poor stacks do signed 16bit maths!
54 */
55#define MAX_TCP_WINDOW 32767U
56
57/* Minimal accepted MSS. It is (60+60+8) - (20+20). */
58#define TCP_MIN_MSS 88U
59
60/* Minimal RCV_MSS. */
61#define TCP_MIN_RCVMSS 536U
62
5d424d5a
JH		 63/* The least MTU to use for probing */
64#define TCP_BASE_MSS 512
65
1da177e4
LT		 66/* After receiving this amount of duplicate ACKs fast retransmit starts. */
67#define TCP_FASTRETRANS_THRESH 3
68
69/* Maximal reordering. */
70#define TCP_MAX_REORDERING 127
71
72/* Maximal number of ACKs sent quickly to accelerate slow-start. */
73#define TCP_MAX_QUICKACKS 16U
74
75/* urg_data states */
76#define TCP_URG_VALID 0x0100
77#define TCP_URG_NOTYET 0x0200
78#define TCP_URG_READ 0x0400
79
80#define TCP_RETR1 3 /*
81 * This is how many retries it does before it
82 * tries to figure out if the gateway is
83 * down. Minimal RFC value is 3; it corresponds
84 * to ~3sec-8min depending on RTO.
85 */
86
87#define TCP_RETR2 15 /*
88 * This should take at least
89 * 90 minutes to time out.
90 * RFC1122 says that the limit is 100 sec.
91 * 15 is ~13-30min depending on RTO.
92 */
93
94#define TCP_SYN_RETRIES 5 /* number of times to retry active opening a
caa20d9a 95 * connection: ~180sec is RFC minimum */
1da177e4
LT		 96
97#define TCP_SYNACK_RETRIES 5 /* number of times to retry passive opening a
caa20d9a 98 * connection: ~180sec is RFC minimum */
1da177e4
LT		 99
100
101#define TCP_ORPHAN_RETRIES 7 /* number of times to retry on an orphaned
102 * socket. 7 is ~50sec-16min.
103 */
104
105
106#define TCP_TIMEWAIT_LEN (60*HZ) /* how long to wait to destroy TIME-WAIT
107 * state, about 60 seconds */
108#define TCP_FIN_TIMEOUT TCP_TIMEWAIT_LEN
109 /* BSD style FIN_WAIT2 deadlock breaker.
110 * It used to be 3min, new value is 60sec,
111 * to combine FIN-WAIT-2 timeout with
112 * TIME-WAIT timer.
113 */
114
115#define TCP_DELACK_MAX ((unsigned)(HZ/5)) /* maximal time to delay before sending an ACK */
116#if HZ >= 100
117#define TCP_DELACK_MIN ((unsigned)(HZ/25)) /* minimal time to delay before sending an ACK */
118#define TCP_ATO_MIN ((unsigned)(HZ/25))
119#else
120#define TCP_DELACK_MIN 4U
121#define TCP_ATO_MIN 4U
122#endif
123#define TCP_RTO_MAX ((unsigned)(120*HZ))
124#define TCP_RTO_MIN ((unsigned)(HZ/5))
125#define TCP_TIMEOUT_INIT ((unsigned)(3*HZ)) /* RFC 1122 initial RTO value */
126
127#define TCP_RESOURCE_PROBE_INTERVAL ((unsigned)(HZ/2U)) /* Maximal interval between probes
128 * for local resources.
129 */
130
131#define TCP_KEEPALIVE_TIME (120*60*HZ) /* two hours */
132#define TCP_KEEPALIVE_PROBES 9 /* Max of 9 keepalive probes */
133#define TCP_KEEPALIVE_INTVL (75*HZ)
134
135#define MAX_TCP_KEEPIDLE 32767
136#define MAX_TCP_KEEPINTVL 32767
137#define MAX_TCP_KEEPCNT 127
138#define MAX_TCP_SYNCNT 127
139
140#define TCP_SYNQ_INTERVAL (HZ/5) /* Period of SYNACK timer */
141#define TCP_SYNQ_HSIZE 512 /* Size of SYNACK hash table */
142
143#define TCP_PAWS_24DAYS (60 * 60 * 24 * 24)
144#define TCP_PAWS_MSL 60 /* Per-host timestamps are invalidated
145 * after this time. It should be equal
146 * (or greater than) TCP_TIMEWAIT_LEN
147 * to provide reliability equal to one
148 * provided by timewait state.
149 */
150#define TCP_PAWS_WINDOW 1 /* Replay window for per-host
151 * timestamps. It must be less than
152 * minimal timewait lifetime.
153 */
1da177e4
LT		 154/*
155 * TCP option
156 */
157
158#define TCPOPT_NOP 1 /* Padding */
159#define TCPOPT_EOL 0 /* End of options */
160#define TCPOPT_MSS 2 /* Segment size negotiating */
161#define TCPOPT_WINDOW 3 /* Window scaling */
162#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
163#define TCPOPT_SACK 5 /* SACK Block */
164#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
165
166/*
167 * TCP option lengths
168 */
169
170#define TCPOLEN_MSS 4
171#define TCPOLEN_WINDOW 3
172#define TCPOLEN_SACK_PERM 2
173#define TCPOLEN_TIMESTAMP 10
174
175/* But this is what stacks really send out. */
176#define TCPOLEN_TSTAMP_ALIGNED 12
177#define TCPOLEN_WSCALE_ALIGNED 4
178#define TCPOLEN_SACKPERM_ALIGNED 4
179#define TCPOLEN_SACK_BASE 2
180#define TCPOLEN_SACK_BASE_ALIGNED 4
181#define TCPOLEN_SACK_PERBLOCK 8
182
1da177e4
LT		 183/* Flags in tp->nonagle */
184#define TCP_NAGLE_OFF 1 /* Nagle's algo is disabled */
185#define TCP_NAGLE_CORK 2 /* Socket is corked */
caa20d9a 186#define TCP_NAGLE_PUSH 4 /* Cork is overridden for already queued data */
1da177e4 187
295ff7ed
ACM		 188extern struct inet_timewait_death_row tcp_death_row;
189
1da177e4 190/* sysctl variables for tcp */
1da177e4
LT		 191extern int sysctl_tcp_timestamps;
192extern int sysctl_tcp_window_scaling;
193extern int sysctl_tcp_sack;
194extern int sysctl_tcp_fin_timeout;
1da177e4
LT		 195extern int sysctl_tcp_keepalive_time;
196extern int sysctl_tcp_keepalive_probes;
197extern int sysctl_tcp_keepalive_intvl;
198extern int sysctl_tcp_syn_retries;
199extern int sysctl_tcp_synack_retries;
200extern int sysctl_tcp_retries1;
201extern int sysctl_tcp_retries2;
202extern int sysctl_tcp_orphan_retries;
203extern int sysctl_tcp_syncookies;
204extern int sysctl_tcp_retrans_collapse;
205extern int sysctl_tcp_stdurg;
206extern int sysctl_tcp_rfc1337;
207extern int sysctl_tcp_abort_on_overflow;
208extern int sysctl_tcp_max_orphans;
1da177e4
LT		 209extern int sysctl_tcp_fack;
210extern int sysctl_tcp_reordering;
211extern int sysctl_tcp_ecn;
212extern int sysctl_tcp_dsack;
213extern int sysctl_tcp_mem[3];
214extern int sysctl_tcp_wmem[3];
215extern int sysctl_tcp_rmem[3];
216extern int sysctl_tcp_app_win;
217extern int sysctl_tcp_adv_win_scale;
218extern int sysctl_tcp_tw_reuse;
219extern int sysctl_tcp_frto;
220extern int sysctl_tcp_low_latency;
95937825 221extern int sysctl_tcp_dma_copybreak;
1da177e4 222extern int sysctl_tcp_nometrics_save;
1da177e4
LT		 223extern int sysctl_tcp_moderate_rcvbuf;
224extern int sysctl_tcp_tso_win_divisor;
9772efb9 225extern int sysctl_tcp_abc;
5d424d5a
JH		 226extern int sysctl_tcp_mtu_probing;
227extern int sysctl_tcp_base_mss;
15d99e02 228extern int sysctl_tcp_workaround_signed_windows;
35089bb2 229extern int sysctl_tcp_slow_start_after_idle;
1da177e4
LT		 230
231extern atomic_t tcp_memory_allocated;
232extern atomic_t tcp_sockets_allocated;
233extern int tcp_memory_pressure;
234
1da177e4
LT		 235/*
236 * The next routines deal with comparing 32 bit unsigned ints
237 * and worry about wraparound (automatic with unsigned arithmetic).
238 */
239
240static inline int before(__u32 seq1, __u32 seq2)
241{
242 return (__s32)(seq1-seq2) < 0;
243}
244
245static inline int after(__u32 seq1, __u32 seq2)
246{
247 return (__s32)(seq2-seq1) < 0;
248}
249
250
251/* is s2<=s1<=s3 ? */
252static inline int between(__u32 seq1, __u32 seq2, __u32 seq3)
253{
254 return seq3 - seq2 >= seq1 - seq2;
255}
256
257
258extern struct proto tcp_prot;
259
260DECLARE_SNMP_STAT(struct tcp_mib, tcp_statistics);
261#define TCP_INC_STATS(field) SNMP_INC_STATS(tcp_statistics, field)
262#define TCP_INC_STATS_BH(field) SNMP_INC_STATS_BH(tcp_statistics, field)
263#define TCP_INC_STATS_USER(field) SNMP_INC_STATS_USER(tcp_statistics, field)
264#define TCP_DEC_STATS(field) SNMP_DEC_STATS(tcp_statistics, field)
265#define TCP_ADD_STATS_BH(field, val) SNMP_ADD_STATS_BH(tcp_statistics, field, val)
266#define TCP_ADD_STATS_USER(field, val) SNMP_ADD_STATS_USER(tcp_statistics, field, val)
267
1da177e4
LT		 268extern void tcp_v4_err(struct sk_buff *skb, u32);
269
270extern void tcp_shutdown (struct sock *sk, int how);
271
272extern int tcp_v4_rcv(struct sk_buff *skb);
273
274extern int tcp_v4_remember_stamp(struct sock *sk);
275
8feaf0c0 276extern int tcp_v4_tw_remember_stamp(struct inet_timewait_sock *tw);
1da177e4
LT		 277
278extern int tcp_sendmsg(struct kiocb *iocb, struct sock *sk,
279 struct msghdr *msg, size_t size);
280extern ssize_t tcp_sendpage(struct socket *sock, struct page *page, int offset, size_t size, int flags);
281
282extern int tcp_ioctl(struct sock *sk,
283 int cmd,
284 unsigned long arg);
285
286extern int tcp_rcv_state_process(struct sock *sk,
287 struct sk_buff *skb,
288 struct tcphdr *th,
289 unsigned len);
290
291extern int tcp_rcv_established(struct sock *sk,
292 struct sk_buff *skb,
293 struct tcphdr *th,
294 unsigned len);
295
296extern void tcp_rcv_space_adjust(struct sock *sk);
297
0e4b4992
CL		 298extern void tcp_cleanup_rbuf(struct sock *sk, int copied);
299
6d6ee43e
ACM		 300extern int tcp_twsk_unique(struct sock *sk,
301 struct sock *sktw, void *twp);
302
463c84b9
ACM		 303static inline void tcp_dec_quickack_mode(struct sock *sk,
304 const unsigned int pkts)
1da177e4 305{
463c84b9 306 struct inet_connection_sock *icsk = inet_csk(sk);
fc6415bc 307
463c84b9
ACM		 308 if (icsk->icsk_ack.quick) {
309 if (pkts >= icsk->icsk_ack.quick) {
310 icsk->icsk_ack.quick = 0;
fc6415bc 311 /* Leaving quickack mode we deflate ATO. */
463c84b9 312 icsk->icsk_ack.ato = TCP_ATO_MIN;
fc6415bc 313 } else
463c84b9 314 icsk->icsk_ack.quick -= pkts;
1da177e4
LT		 315 }
316}
317
463c84b9 318extern void tcp_enter_quickack_mode(struct sock *sk);
1da177e4 319
1da177e4
LT		 320static inline void tcp_clear_options(struct tcp_options_received *rx_opt)
321{
322 rx_opt->tstamp_ok = rx_opt->sack_ok = rx_opt->wscale_ok = rx_opt->snd_wscale = 0;
323}
324
325enum tcp_tw_status
326{
327 TCP_TW_SUCCESS = 0,
328 TCP_TW_RST = 1,
329 TCP_TW_ACK = 2,
330 TCP_TW_SYN = 3
331};
332
333
8feaf0c0 334extern enum tcp_tw_status tcp_timewait_state_process(struct inet_timewait_sock *tw,
1da177e4 335 struct sk_buff *skb,
8feaf0c0 336 const struct tcphdr *th);
1da177e4
LT		 337
338extern struct sock * tcp_check_req(struct sock *sk,struct sk_buff *skb,
60236fdd
ACM		 339 struct request_sock *req,
340 struct request_sock **prev);
1da177e4
LT		 341extern int tcp_child_process(struct sock *parent,
342 struct sock *child,
343 struct sk_buff *skb);
344extern void tcp_enter_frto(struct sock *sk);
345extern void tcp_enter_loss(struct sock *sk, int how);
346extern void tcp_clear_retrans(struct tcp_sock *tp);
347extern void tcp_update_metrics(struct sock *sk);
348
349extern void tcp_close(struct sock *sk,
350 long timeout);
1da177e4
LT		 351extern unsigned int tcp_poll(struct file * file, struct socket *sock, struct poll_table_struct *wait);
352
353extern int tcp_getsockopt(struct sock *sk, int level,
354 int optname,
355 char __user *optval,
356 int __user *optlen);
357extern int tcp_setsockopt(struct sock *sk, int level,
358 int optname, char __user *optval,
359 int optlen);
3fdadf7d
DM		 360extern int compat_tcp_getsockopt(struct sock *sk,
361 int level, int optname,
362 char __user *optval, int __user *optlen);
363extern int compat_tcp_setsockopt(struct sock *sk,
364 int level, int optname,
365 char __user *optval, int optlen);
1da177e4
LT		 366extern void tcp_set_keepalive(struct sock *sk, int val);
367extern int tcp_recvmsg(struct kiocb *iocb, struct sock *sk,
368 struct msghdr *msg,
369 size_t len, int nonblock,
370 int flags, int *addr_len);
371
1da177e4
LT		 372extern void tcp_parse_options(struct sk_buff *skb,
373 struct tcp_options_received *opt_rx,
374 int estab);
375
376/*
377 * TCP v4 functions exported for the inet6 API
378 */
379
8292a17a 380extern void tcp_v4_send_check(struct sock *sk, int len,
1da177e4
LT		 381 struct sk_buff *skb);
382
383extern int tcp_v4_conn_request(struct sock *sk,
384 struct sk_buff *skb);
385
386extern struct sock * tcp_create_openreq_child(struct sock *sk,
60236fdd 387 struct request_sock *req,
1da177e4
LT		 388 struct sk_buff *skb);
389
390extern struct sock * tcp_v4_syn_recv_sock(struct sock *sk,
391 struct sk_buff *skb,
60236fdd 392 struct request_sock *req,
1da177e4
LT		 393 struct dst_entry *dst);
394
395extern int tcp_v4_do_rcv(struct sock *sk,
396 struct sk_buff *skb);
397
398extern int tcp_v4_connect(struct sock *sk,
399 struct sockaddr *uaddr,
400 int addr_len);
401
402extern int tcp_connect(struct sock *sk);
403
404extern struct sk_buff * tcp_make_synack(struct sock *sk,
405 struct dst_entry *dst,
60236fdd 406 struct request_sock *req);
1da177e4
LT		 407
408extern int tcp_disconnect(struct sock *sk, int flags);
409
410extern void tcp_unhash(struct sock *sk);
411
1da177e4
LT		 412/* From syncookies.c */
413extern struct sock *cookie_v4_check(struct sock *sk, struct sk_buff *skb,
414 struct ip_options *opt);
415extern __u32 cookie_v4_init_sequence(struct sock *sk, struct sk_buff *skb,
416 __u16 *mss);
417
418/* tcp_output.c */
419
f6302d1d 420extern void __tcp_push_pending_frames(struct sock *sk, struct tcp_sock *tp,
a2e2a59c 421 unsigned int cur_mss, int nonagle);
f6302d1d 422extern int tcp_may_send_now(struct sock *sk, struct tcp_sock *tp);
1da177e4
LT		 423extern int tcp_retransmit_skb(struct sock *, struct sk_buff *);
424extern void tcp_xmit_retransmit_queue(struct sock *);
425extern void tcp_simple_retransmit(struct sock *);
426extern int tcp_trim_head(struct sock *, struct sk_buff *, u32);
6475be16 427extern int tcp_fragment(struct sock *, struct sk_buff *, u32, unsigned int);
1da177e4
LT		 428
429extern void tcp_send_probe0(struct sock *);
430extern void tcp_send_partial(struct sock *);
431extern int tcp_write_wakeup(struct sock *);
432extern void tcp_send_fin(struct sock *sk);
dd0fc66f 433extern void tcp_send_active_reset(struct sock *sk, gfp_t priority);
1da177e4 434extern int tcp_send_synack(struct sock *);
c1b4a7e6 435extern void tcp_push_one(struct sock *, unsigned int mss_now);
1da177e4
LT		 436extern void tcp_send_ack(struct sock *sk);
437extern void tcp_send_delayed_ack(struct sock *sk);
438
a762a980
DM		 439/* tcp_input.c */
440extern void tcp_cwnd_application_limited(struct sock *sk);
441
1da177e4
LT		 442/* tcp_timer.c */
443extern void tcp_init_xmit_timers(struct sock *);
463c84b9
ACM		 444static inline void tcp_clear_xmit_timers(struct sock *sk)
445{
446 inet_csk_clear_xmit_timers(sk);
447}
1da177e4 448
1da177e4
LT		 449extern unsigned int tcp_sync_mss(struct sock *sk, u32 pmtu);
450extern unsigned int tcp_current_mss(struct sock *sk, int large);
451
17b085ea 452/* tcp.c */
1da177e4
LT		 453extern void tcp_get_info(struct sock *, struct tcp_info *);
454
455/* Read 'sendfile()'-style from a TCP socket */
456typedef int (*sk_read_actor_t)(read_descriptor_t *, struct sk_buff *,
457 unsigned int, size_t);
458extern int tcp_read_sock(struct sock *sk, read_descriptor_t *desc,
459 sk_read_actor_t recv_actor);
460
40efc6fa 461extern void tcp_initialize_rcv_mss(struct sock *sk);
1da177e4 462
5d424d5a
JH		 463extern int tcp_mtu_to_mss(struct sock *sk, int pmtu);
464extern int tcp_mss_to_mtu(struct sock *sk, int mss);
465extern void tcp_mtup_init(struct sock *sk);
466
40efc6fa 467static inline void __tcp_fast_path_on(struct tcp_sock *tp, u32 snd_wnd)
1da177e4
LT		 468{
469 tp->pred_flags = htonl((tp->tcp_header_len << 26) |
470 ntohl(TCP_FLAG_ACK) |
471 snd_wnd);
472}
473
40efc6fa 474static inline void tcp_fast_path_on(struct tcp_sock *tp)
1da177e4
LT		 475{
476 __tcp_fast_path_on(tp, tp->snd_wnd >> tp->rx_opt.snd_wscale);
477}
478
479static inline void tcp_fast_path_check(struct sock *sk, struct tcp_sock *tp)
480{
b03efcfb 481 if (skb_queue_empty(&tp->out_of_order_queue) &&
1da177e4
LT		 482 tp->rcv_wnd &&
483 atomic_read(&sk->sk_rmem_alloc) < sk->sk_rcvbuf &&
484 !tp->urg_data)
485 tcp_fast_path_on(tp);
486}
487
488/* Compute the actual receive window we are currently advertising.
489 * Rcv_nxt can be after the window if our peer push more data
490 * than the offered window.
491 */
40efc6fa 492static inline u32 tcp_receive_window(const struct tcp_sock *tp)
1da177e4
LT		 493{
494 s32 win = tp->rcv_wup + tp->rcv_wnd - tp->rcv_nxt;
495
496 if (win < 0)
497 win = 0;
498 return (u32) win;
499}
500
501/* Choose a new window, without checks for shrinking, and without
502 * scaling applied to the result. The caller does these things
503 * if necessary. This is a "raw" window selection.
504 */
505extern u32 __tcp_select_window(struct sock *sk);
506
507/* TCP timestamps are only 32-bits, this causes a slight
508 * complication on 64-bit systems since we store a snapshot
31f34269
SH		 509 * of jiffies in the buffer control blocks below. We decided
510 * to use only the low 32-bits of jiffies and hide the ugly
1da177e4
LT		 511 * casts with the following macro.
512 */
513#define tcp_time_stamp ((__u32)(jiffies))
514
caa20d9a 515/* This is what the send packet queuing engine uses to pass
1da177e4
LT		 516 * TCP per-packet control information to the transmission
517 * code. We also store the host-order sequence numbers in
518 * here too. This is 36 bytes on 32-bit architectures,
519 * 40 bytes on 64-bit machines, if this grows please adjust
520 * skbuff.h:skbuff->cb[xxx] size appropriately.
521 */
522struct tcp_skb_cb {
523 union {
524 struct inet_skb_parm h4;
525#if defined(CONFIG_IPV6) || defined (CONFIG_IPV6_MODULE)
526 struct inet6_skb_parm h6;
527#endif
528 } header; /* For incoming frames */
529 __u32 seq; /* Starting sequence number */
530 __u32 end_seq; /* SEQ + FIN + SYN + datalen */
531 __u32 when; /* used to compute rtt's */
532 __u8 flags; /* TCP header flags. */
533
534 /* NOTE: These must match up to the flags byte in a
535 * real TCP header.
536 */
537#define TCPCB_FLAG_FIN 0x01
538#define TCPCB_FLAG_SYN 0x02
539#define TCPCB_FLAG_RST 0x04
540#define TCPCB_FLAG_PSH 0x08
541#define TCPCB_FLAG_ACK 0x10
542#define TCPCB_FLAG_URG 0x20
543#define TCPCB_FLAG_ECE 0x40
544#define TCPCB_FLAG_CWR 0x80
545
546 __u8 sacked; /* State flags for SACK/FACK. */
547#define TCPCB_SACKED_ACKED 0x01 /* SKB ACK'd by a SACK block */
548#define TCPCB_SACKED_RETRANS 0x02 /* SKB retransmitted */
549#define TCPCB_LOST 0x04 /* SKB is lost */
550#define TCPCB_TAGBITS 0x07 /* All tag bits */
551
552#define TCPCB_EVER_RETRANS 0x80 /* Ever retransmitted frame */
553#define TCPCB_RETRANS (TCPCB_SACKED_RETRANS|TCPCB_EVER_RETRANS)
554
caa20d9a 555#define TCPCB_URG 0x20 /* Urgent pointer advanced here */
1da177e4
LT		 556
557#define TCPCB_AT_TAIL (TCPCB_URG)
558
559 __u16 urg_ptr; /* Valid w/URG flags is set. */
560 __u32 ack_seq; /* Sequence number ACK'd */
561};
562
563#define TCP_SKB_CB(__skb) ((struct tcp_skb_cb *)&((__skb)->cb[0]))
564
565#include <net/tcp_ecn.h>
566
567/* Due to TSO, an SKB can be composed of multiple actual
568 * packets. To keep these tracked properly, we use this.
569 */
570static inline int tcp_skb_pcount(const struct sk_buff *skb)
571{
7967168c 572 return skb_shinfo(skb)->gso_segs;
1da177e4
LT		 573}
574
575/* This is valid iff tcp_skb_pcount() > 1. */
576static inline int tcp_skb_mss(const struct sk_buff *skb)
577{
7967168c 578 return skb_shinfo(skb)->gso_size;
1da177e4
LT		 579}
580
581static inline void tcp_dec_pcount_approx(__u32 *count,
582 const struct sk_buff *skb)
583{
584 if (*count) {
585 *count -= tcp_skb_pcount(skb);
586 if ((int)*count < 0)
587 *count = 0;
588 }
589}
590
591static inline void tcp_packets_out_inc(struct sock *sk,
592 struct tcp_sock *tp,
593 const struct sk_buff *skb)
594{
595 int orig = tp->packets_out;
596
597 tp->packets_out += tcp_skb_pcount(skb);
598 if (!orig)
3f421baa
ACM		 599 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
600 inet_csk(sk)->icsk_rto, TCP_RTO_MAX);
1da177e4
LT		 601}
602
603static inline void tcp_packets_out_dec(struct tcp_sock *tp,
604 const struct sk_buff *skb)
605{
606 tp->packets_out -= tcp_skb_pcount(skb);
607}
608
317a76f9
SH		 609/* Events passed to congestion control interface */
610enum tcp_ca_event {
611 CA_EVENT_TX_START, /* first transmit when no packets in flight */
612 CA_EVENT_CWND_RESTART, /* congestion window restart */
613 CA_EVENT_COMPLETE_CWR, /* end of congestion recovery */
614 CA_EVENT_FRTO, /* fast recovery timeout */
615 CA_EVENT_LOSS, /* loss timeout */
616 CA_EVENT_FAST_ACK, /* in sequence ack */
617 CA_EVENT_SLOW_ACK, /* other ack */
618};
619
620/*
621 * Interface for adding new TCP congestion control handlers
622 */
623#define TCP_CA_NAME_MAX 16
624struct tcp_congestion_ops {
625 struct list_head list;
626
627 /* initialize private data (optional) */
6687e988 628 void (*init)(struct sock *sk);
317a76f9 629 /* cleanup private data (optional) */
6687e988 630 void (*release)(struct sock *sk);
317a76f9
SH		 631
632 /* return slow start threshold (required) */
6687e988 633 u32 (*ssthresh)(struct sock *sk);
317a76f9 634 /* lower bound for congestion window (optional) */
72dc5b92 635 u32 (*min_cwnd)(const struct sock *sk);
317a76f9 636 /* do new cwnd calculation (required) */
6687e988 637 void (*cong_avoid)(struct sock *sk, u32 ack,
317a76f9
SH		 638 u32 rtt, u32 in_flight, int good_ack);
639 /* round trip time sample per acked packet (optional) */
6687e988 640 void (*rtt_sample)(struct sock *sk, u32 usrtt);
317a76f9 641 /* call before changing ca_state (optional) */
6687e988 642 void (*set_state)(struct sock *sk, u8 new_state);
317a76f9 643 /* call when cwnd event occurs (optional) */
6687e988 644 void (*cwnd_event)(struct sock *sk, enum tcp_ca_event ev);
317a76f9 645 /* new value of cwnd after loss (optional) */
6687e988 646 u32 (*undo_cwnd)(struct sock *sk);
317a76f9 647 /* hook for packet ack accounting (optional) */
6687e988 648 void (*pkts_acked)(struct sock *sk, u32 num_acked);
73c1f4a0 649 /* get info for inet_diag (optional) */
6687e988 650 void (*get_info)(struct sock *sk, u32 ext, struct sk_buff *skb);
317a76f9
SH		 651
652 char name[TCP_CA_NAME_MAX];
653 struct module *owner;
654};
655
656extern int tcp_register_congestion_control(struct tcp_congestion_ops *type);
657extern void tcp_unregister_congestion_control(struct tcp_congestion_ops *type);
658
6687e988
ACM		 659extern void tcp_init_congestion_control(struct sock *sk);
660extern void tcp_cleanup_congestion_control(struct sock *sk);
317a76f9
SH		 661extern int tcp_set_default_congestion_control(const char *name);
662extern void tcp_get_default_congestion_control(char *name);
6687e988 663extern int tcp_set_congestion_control(struct sock *sk, const char *name);
40efc6fa 664extern void tcp_slow_start(struct tcp_sock *tp);
317a76f9 665
5f8ef48d 666extern struct tcp_congestion_ops tcp_init_congestion_ops;
6687e988
ACM		 667extern u32 tcp_reno_ssthresh(struct sock *sk);
668extern void tcp_reno_cong_avoid(struct sock *sk, u32 ack,
317a76f9 669 u32 rtt, u32 in_flight, int flag);
72dc5b92 670extern u32 tcp_reno_min_cwnd(const struct sock *sk);
a8acfbac 671extern struct tcp_congestion_ops tcp_reno;
317a76f9 672
6687e988 673static inline void tcp_set_ca_state(struct sock *sk, const u8 ca_state)
317a76f9 674{
6687e988
ACM		 675 struct inet_connection_sock *icsk = inet_csk(sk);
676
677 if (icsk->icsk_ca_ops->set_state)
678 icsk->icsk_ca_ops->set_state(sk, ca_state);
679 icsk->icsk_ca_state = ca_state;
317a76f9
SH		 680}
681
6687e988 682static inline void tcp_ca_event(struct sock *sk, const enum tcp_ca_event event)
317a76f9 683{
6687e988
ACM		 684 const struct inet_connection_sock *icsk = inet_csk(sk);
685
686 if (icsk->icsk_ca_ops->cwnd_event)
687 icsk->icsk_ca_ops->cwnd_event(sk, event);
317a76f9
SH		 688}
689
1da177e4
LT		 690/* This determines how many packets are "in the network" to the best
691 * of our knowledge. In many cases it is conservative, but where
692 * detailed information is available from the receiver (via SACK
693 * blocks etc.) we can make more aggressive calculations.
694 *
695 * Use this for decisions involving congestion control, use just
696 * tp->packets_out to determine if the send queue is empty or not.
697 *
698 * Read this equation as:
699 *
700 * "Packets sent once on transmission queue" MINUS
701 * "Packets left network, but not honestly ACKed yet" PLUS
702 * "Packets fast retransmitted"
703 */
40efc6fa 704static inline unsigned int tcp_packets_in_flight(const struct tcp_sock *tp)
1da177e4
LT		 705{
706 return (tp->packets_out - tp->left_out + tp->retrans_out);
707}
708
1da177e4
LT		 709/* If cwnd > ssthresh, we may raise ssthresh to be half-way to cwnd.
710 * The exception is rate halving phase, when cwnd is decreasing towards
711 * ssthresh.
712 */
6687e988 713static inline __u32 tcp_current_ssthresh(const struct sock *sk)
1da177e4 714{
6687e988
ACM		 715 const struct tcp_sock *tp = tcp_sk(sk);
716 if ((1 << inet_csk(sk)->icsk_ca_state) & (TCPF_CA_CWR | TCPF_CA_Recovery))
1da177e4
LT		 717 return tp->snd_ssthresh;
718 else
719 return max(tp->snd_ssthresh,
720 ((tp->snd_cwnd >> 1) +
721 (tp->snd_cwnd >> 2)));
722}
723
724static inline void tcp_sync_left_out(struct tcp_sock *tp)
725{
726 if (tp->rx_opt.sack_ok &&
727 (tp->sacked_out >= tp->packets_out - tp->lost_out))
728 tp->sacked_out = tp->packets_out - tp->lost_out;
729 tp->left_out = tp->sacked_out + tp->lost_out;
730}
731
40efc6fa 732extern void tcp_enter_cwr(struct sock *sk);
1da177e4
LT		 733extern __u32 tcp_init_cwnd(struct tcp_sock *tp, struct dst_entry *dst);
734
735/* Slow start with delack produces 3 packets of burst, so that
736 * it is safe "de facto".
737 */
738static __inline__ __u32 tcp_max_burst(const struct tcp_sock *tp)
739{
740 return 3;
741}
742
f4805ede
SH		 743/* RFC2861 Check whether we are limited by application or congestion window
744 * This is the inverse of cwnd check in tcp_tso_should_defer
745 */
746static inline int tcp_is_cwnd_limited(const struct sock *sk, u32 in_flight)
747{
748 const struct tcp_sock *tp = tcp_sk(sk);
749 u32 left;
750
751 if (in_flight >= tp->snd_cwnd)
752 return 1;
753
754 if (!(sk->sk_route_caps & NETIF_F_TSO))
755 return 0;
756
757 left = tp->snd_cwnd - in_flight;
758 if (sysctl_tcp_tso_win_divisor)
759 return left * sysctl_tcp_tso_win_divisor < tp->snd_cwnd;
760 else
761 return left <= tcp_max_burst(tp);
762}
763
40efc6fa
SH		 764static inline void tcp_minshall_update(struct tcp_sock *tp, int mss,
765 const struct sk_buff *skb)
1da177e4
LT		 766{
767 if (skb->len < mss)
768 tp->snd_sml = TCP_SKB_CB(skb)->end_seq;
769}
770
40efc6fa 771static inline void tcp_check_probe_timer(struct sock *sk, struct tcp_sock *tp)
1da177e4 772{
463c84b9
ACM		 773 const struct inet_connection_sock *icsk = inet_csk(sk);
774 if (!tp->packets_out && !icsk->icsk_pending)
3f421baa
ACM		 775 inet_csk_reset_xmit_timer(sk, ICSK_TIME_PROBE0,
776 icsk->icsk_rto, TCP_RTO_MAX);
1da177e4
LT		 777}
778
40efc6fa
SH		 779static inline void tcp_push_pending_frames(struct sock *sk,
780 struct tcp_sock *tp)
1da177e4
LT		 781{
782 __tcp_push_pending_frames(sk, tp, tcp_current_mss(sk, 1), tp->nonagle);
783}
784
40efc6fa 785static inline void tcp_init_wl(struct tcp_sock *tp, u32 ack, u32 seq)
1da177e4
LT		 786{
787 tp->snd_wl1 = seq;
788}
789
40efc6fa 790static inline void tcp_update_wl(struct tcp_sock *tp, u32 ack, u32 seq)
1da177e4
LT		 791{
792 tp->snd_wl1 = seq;
793}
794
1da177e4
LT		 795/*
796 * Calculate(/check) TCP checksum
797 */
40efc6fa
SH		 798static inline u16 tcp_v4_check(struct tcphdr *th, int len,
799 unsigned long saddr, unsigned long daddr,
800 unsigned long base)
1da177e4
LT		 801{
802 return csum_tcpudp_magic(saddr,daddr,len,IPPROTO_TCP,base);
803}
804
40efc6fa 805static inline int __tcp_checksum_complete(struct sk_buff *skb)
1da177e4 806{
fb286bb2 807 return __skb_checksum_complete(skb);
1da177e4
LT		 808}
809
40efc6fa 810static inline int tcp_checksum_complete(struct sk_buff *skb)
1da177e4
LT		 811{
812 return skb->ip_summed != CHECKSUM_UNNECESSARY &&
813 __tcp_checksum_complete(skb);
814}
815
816/* Prequeue for VJ style copy to user, combined with checksumming. */
817
40efc6fa 818static inline void tcp_prequeue_init(struct tcp_sock *tp)
1da177e4
LT		 819{
820 tp->ucopy.task = NULL;
821 tp->ucopy.len = 0;
822 tp->ucopy.memory = 0;
823 skb_queue_head_init(&tp->ucopy.prequeue);
97fc2f08
CL		 824#ifdef CONFIG_NET_DMA
825 tp->ucopy.dma_chan = NULL;
826 tp->ucopy.wakeup = 0;
827 tp->ucopy.pinned_list = NULL;
828 tp->ucopy.dma_cookie = 0;
829#endif
1da177e4
LT		 830}
831
832/* Packet is added to VJ-style prequeue for processing in process
833 * context, if a reader task is waiting. Apparently, this exciting
834 * idea (VJ's mail "Re: query about TCP header on tcp-ip" of 07 Sep 93)
835 * failed somewhere. Latency? Burstiness? Well, at least now we will
836 * see, why it failed. 8)8) --ANK
837 *
838 * NOTE: is this not too big to inline?
839 */
40efc6fa 840static inline int tcp_prequeue(struct sock *sk, struct sk_buff *skb)
1da177e4
LT		 841{
842 struct tcp_sock *tp = tcp_sk(sk);
843
844 if (!sysctl_tcp_low_latency && tp->ucopy.task) {
845 __skb_queue_tail(&tp->ucopy.prequeue, skb);
846 tp->ucopy.memory += skb->truesize;
847 if (tp->ucopy.memory > sk->sk_rcvbuf) {
848 struct sk_buff *skb1;
849
850 BUG_ON(sock_owned_by_user(sk));
851
852 while ((skb1 = __skb_dequeue(&tp->ucopy.prequeue)) != NULL) {
853 sk->sk_backlog_rcv(sk, skb1);
854 NET_INC_STATS_BH(LINUX_MIB_TCPPREQUEUEDROPPED);
855 }
856
857 tp->ucopy.memory = 0;
858 } else if (skb_queue_len(&tp->ucopy.prequeue) == 1) {
859 wake_up_interruptible(sk->sk_sleep);
463c84b9
ACM		 860 if (!inet_csk_ack_scheduled(sk))
861 inet_csk_reset_xmit_timer(sk, ICSK_TIME_DACK,
3f421baa
ACM		 862 (3 * TCP_RTO_MIN) / 4,
863 TCP_RTO_MAX);
1da177e4
LT		 864 }
865 return 1;
866 }
867 return 0;
868}
869
870
871#undef STATE_TRACE
872
873#ifdef STATE_TRACE
874static const char *statename[]={
875 "Unused","Established","Syn Sent","Syn Recv",
876 "Fin Wait 1","Fin Wait 2","Time Wait", "Close",
877 "Close Wait","Last ACK","Listen","Closing"
878};
879#endif
880
40efc6fa 881static inline void tcp_set_state(struct sock *sk, int state)
1da177e4
LT		 882{
883 int oldstate = sk->sk_state;
884
885 switch (state) {
886 case TCP_ESTABLISHED:
887 if (oldstate != TCP_ESTABLISHED)
888 TCP_INC_STATS(TCP_MIB_CURRESTAB);
889 break;
890
891 case TCP_CLOSE:
892 if (oldstate == TCP_CLOSE_WAIT || oldstate == TCP_ESTABLISHED)
893 TCP_INC_STATS(TCP_MIB_ESTABRESETS);
894
895 sk->sk_prot->unhash(sk);
463c84b9 896 if (inet_csk(sk)->icsk_bind_hash &&
1da177e4 897 !(sk->sk_userlocks & SOCK_BINDPORT_LOCK))
2d8c4ce5 898 inet_put_port(&tcp_hashinfo, sk);
1da177e4
LT		 899 /* fall through */
900 default:
901 if (oldstate==TCP_ESTABLISHED)
902 TCP_DEC_STATS(TCP_MIB_CURRESTAB);
903 }
904
905 /* Change state AFTER socket is unhashed to avoid closed
906 * socket sitting in hash tables.
907 */
908 sk->sk_state = state;
909
910#ifdef STATE_TRACE
911 SOCK_DEBUG(sk, "TCP sk=%p, State %s -> %s\n",sk, statename[oldstate],statename[state]);
912#endif
913}
914
40efc6fa 915static inline void tcp_done(struct sock *sk)
1da177e4
LT		 916{
917 tcp_set_state(sk, TCP_CLOSE);
918 tcp_clear_xmit_timers(sk);
919
920 sk->sk_shutdown = SHUTDOWN_MASK;
921
922 if (!sock_flag(sk, SOCK_DEAD))
923 sk->sk_state_change(sk);
924 else
0a5578cf 925 inet_csk_destroy_sock(sk);
1da177e4
LT		 926}
927
40efc6fa 928static inline void tcp_sack_reset(struct tcp_options_received *rx_opt)
1da177e4
LT		 929{
930 rx_opt->dsack = 0;
931 rx_opt->eff_sacks = 0;
932 rx_opt->num_sacks = 0;
933}
934
1da177e4
LT		 935/* Determine a window scaling and initial window to offer. */
936extern void tcp_select_initial_window(int __space, __u32 mss,
937 __u32 *rcv_wnd, __u32 *window_clamp,
938 int wscale_ok, __u8 *rcv_wscale);
939
940static inline int tcp_win_from_space(int space)
941{
942 return sysctl_tcp_adv_win_scale<=0 ?
943 (space>>(-sysctl_tcp_adv_win_scale)) :
944 space - (space>>sysctl_tcp_adv_win_scale);
945}
946
947/* Note: caller must be prepared to deal with negative returns */
948static inline int tcp_space(const struct sock *sk)
949{
950 return tcp_win_from_space(sk->sk_rcvbuf -
951 atomic_read(&sk->sk_rmem_alloc));
952}
953
954static inline int tcp_full_space(const struct sock *sk)
955{
956 return tcp_win_from_space(sk->sk_rcvbuf);
957}
958
40efc6fa
SH		 959static inline void tcp_openreq_init(struct request_sock *req,
960 struct tcp_options_received *rx_opt,
961 struct sk_buff *skb)
1da177e4 962{
2e6599cb
ACM		 963 struct inet_request_sock *ireq = inet_rsk(req);
964
1da177e4 965 req->rcv_wnd = 0; /* So that tcp_send_synack() knows! */
2e6599cb 966 tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
1da177e4
LT		 967 req->mss = rx_opt->mss_clamp;
968 req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
2e6599cb
ACM		 969 ireq->tstamp_ok = rx_opt->tstamp_ok;
970 ireq->sack_ok = rx_opt->sack_ok;
971 ireq->snd_wscale = rx_opt->snd_wscale;
972 ireq->wscale_ok = rx_opt->wscale_ok;
973 ireq->acked = 0;
974 ireq->ecn_ok = 0;
975 ireq->rmt_port = skb->h.th->source;
1da177e4
LT		 976}
977
978extern void tcp_enter_memory_pressure(void);
979
1da177e4
LT		 980static inline int keepalive_intvl_when(const struct tcp_sock *tp)
981{
982 return tp->keepalive_intvl ? : sysctl_tcp_keepalive_intvl;
983}
984
985static inline int keepalive_time_when(const struct tcp_sock *tp)
986{
987 return tp->keepalive_time ? : sysctl_tcp_keepalive_time;
988}
989
463c84b9 990static inline int tcp_fin_time(const struct sock *sk)
1da177e4 991{
463c84b9
ACM		 992 int fin_timeout = tcp_sk(sk)->linger2 ? : sysctl_tcp_fin_timeout;
993 const int rto = inet_csk(sk)->icsk_rto;
1da177e4 994
463c84b9
ACM		 995 if (fin_timeout < (rto << 2) - (rto >> 1))
996 fin_timeout = (rto << 2) - (rto >> 1);
1da177e4
LT		 997
998 return fin_timeout;
999}
1000
1001static inline int tcp_paws_check(const struct tcp_options_received *rx_opt, int rst)
1002{
1003 if ((s32)(rx_opt->rcv_tsval - rx_opt->ts_recent) >= 0)
1004 return 0;
1005 if (xtime.tv_sec >= rx_opt->ts_recent_stamp + TCP_PAWS_24DAYS)
1006 return 0;
1007
1008 /* RST segments are not recommended to carry timestamp,
1009 and, if they do, it is recommended to ignore PAWS because
1010 "their cleanup function should take precedence over timestamps."
1011 Certainly, it is mistake. It is necessary to understand the reasons
1012 of this constraint to relax it: if peer reboots, clock may go
1013 out-of-sync and half-open connections will not be reset.
1014 Actually, the problem would be not existing if all
1015 the implementations followed draft about maintaining clock
1016 via reboots. Linux-2.2 DOES NOT!
1017
1018 However, we can relax time bounds for RST segments to MSL.
1019 */
1020 if (rst && xtime.tv_sec >= rx_opt->ts_recent_stamp + TCP_PAWS_MSL)
1021 return 0;
1022 return 1;
1023}
1024
1da177e4
LT		 1025#define TCP_CHECK_TIMER(sk) do { } while (0)
1026
1027static inline int tcp_use_frto(const struct sock *sk)
1028{
1029 const struct tcp_sock *tp = tcp_sk(sk);
1030
1031 /* F-RTO must be activated in sysctl and there must be some
1032 * unsent new data, and the advertised window should allow
1033 * sending it.
1034 */
1035 return (sysctl_tcp_frto && sk->sk_send_head &&
1036 !after(TCP_SKB_CB(sk->sk_send_head)->end_seq,
1037 tp->snd_una + tp->snd_wnd));
1038}
1039
1040static inline void tcp_mib_init(void)
1041{
1042 /* See RFC 2012 */
1043 TCP_ADD_STATS_USER(TCP_MIB_RTOALGORITHM, 1);
1044 TCP_ADD_STATS_USER(TCP_MIB_RTOMIN, TCP_RTO_MIN*1000/HZ);
1045 TCP_ADD_STATS_USER(TCP_MIB_RTOMAX, TCP_RTO_MAX*1000/HZ);
1046 TCP_ADD_STATS_USER(TCP_MIB_MAXCONN, -1);
1047}
1048
6a438bbe
SH		 1049/*from STCP */
1050static inline void clear_all_retrans_hints(struct tcp_sock *tp){
1051 tp->lost_skb_hint = NULL;
1052 tp->scoreboard_skb_hint = NULL;
1053 tp->retransmit_skb_hint = NULL;
1054 tp->forward_skb_hint = NULL;
1055 tp->fastpath_skb_hint = NULL;
1056}
1057
1da177e4
LT		 1058/* /proc */
1059enum tcp_seq_states {
1060 TCP_SEQ_STATE_LISTENING,
1061 TCP_SEQ_STATE_OPENREQ,
1062 TCP_SEQ_STATE_ESTABLISHED,
1063 TCP_SEQ_STATE_TIME_WAIT,
1064};
1065
1066struct tcp_seq_afinfo {
1067 struct module *owner;
1068 char *name;
1069 sa_family_t family;
1070 int (*seq_show) (struct seq_file *m, void *v);
1071 struct file_operations *seq_fops;
1072};
1073
1074struct tcp_iter_state {
1075 sa_family_t family;
1076 enum tcp_seq_states state;
1077 struct sock *syn_wait_sk;
1078 int bucket, sbucket, num, uid;
1079 struct seq_operations seq_ops;
1080};
1081
1082extern int tcp_proc_register(struct tcp_seq_afinfo *afinfo);
1083extern void tcp_proc_unregister(struct tcp_seq_afinfo *afinfo);
1084
20380731
ACM		 1085extern struct request_sock_ops tcp_request_sock_ops;
1086
1087extern int tcp_v4_destroy_sock(struct sock *sk);
1088
576a30eb 1089extern struct sk_buff *tcp_tso_segment(struct sk_buff *skb, int features);
f4c50d99 1090
20380731
ACM		 1091#ifdef CONFIG_PROC_FS
1092extern int tcp4_proc_init(void);
1093extern void tcp4_proc_exit(void);
1094#endif
1095
1096extern void tcp_v4_init(struct net_proto_family *ops);
1097extern void tcp_init(void);
1098
1da177e4 1099#endif /* _TCP_H */
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